HSPA+, the future evolution way of HSDPA (High Speed Downlink Packet Access) and HSUPA (High Speed Downlink Packet Access), has been finished with technologies of OFDM (Orthogonal Frequency Division Multiplexing) and MIMO (Multiple-Input Multiple-Output) in 3GPP (3rd Generation Partnership Project) Release 7. HSPA+ is the enhanced technology of 3GPP HSPA (including HSPDA and HSUPA), and provides low complexity, low cost smooth evolution way from HSPA to LTE (Long Time Evolution) for HSPA operator.
HSPA+ promotes peak data velocity and spectra efficiency by taking the technologies of high order modulation (downlink 64 QAM, uplink 16 QAM), MIMO as well as combination of high order modulation and MIMO and so on. On the other hand, for better supporting packet service, HSPA+ has also taken a series of other enhancement technologies to realize the target such as increasing user capacity, reducing time delay, reducing power consumption of terminal, better supporting VoIP (Voice Over IP) as well as improving multicast/broadcast capability and so on. Compared to HSPA, HSPA+ transfers the function of RNC (Radio Network Controller) to Node B to form completely flat radio access network architecture in system architecture, as shown in FIG. 1. Now the Node B integrating RNC function completely is referred to evolved HSPA Node B, or Node B+ for short. SGSN+ is an SGSN (Serving GPRS Support Node) which is updated and able to support HSPA+ function. UE+ is user terminal equipment which is able to support HSPA+ function. Evolved HSPA+ could use 3GPP Rel-5 and later air interface version, without any modification for air interface HSPA business. After taking the scheme, each Node B+ becomes a node equivalent to RNC with Iu-PS interface being able to connect PS CN directly, and Iu-PS user plane ends at SGSN, while if the network supports direct tunnel function, Iu-PS user plane may also end at GGSN (Gateway GPRS Support Node). Communication between evolved HSPA Nodes B is performed via Iur interface. A Node B+ has the ability of independent networking, and supports complete mobility functions, including a handover between systems and within systems.
As the user plane data could reach GGSN without through RNC after flattening, this means the encryption and integrity protection function of the user plane must transfer forward to Node B+. Current HSPA+ security key hierarchy provided by Ericsson is shown in FIG. 2. Therein, definitions of K, CK (Ciphering Key) and IK (Integrity Key) fully accord with those in UMTS (Universal Mobile Telecommunications System). That is to say, K is root key stored in AuC (Authentication Center) and USIM (UNIVERSAL SUBSCRIBER IDENTITY MODULE), while CK and IK are the ciphering key and the integrity key computed from K when user equipment and HSS (Home Subscriber Server) perform AKA (Authentication and Key Agreement). In UMTS, RNC uses CK and IK to perform ciphering and integrity protection for data. As RNC function is completely transferred to Node B+ in HSPA+ architecture, both ciphering and decryption are needed to perform at Node B+. But Node B+ is in unsafe condition and security is not very good. Therefore, HSPA+ brings in a key hierarchy similar to EUTRAN (Evolved Universal Terrestrial Radio Access Network), i.e. UTRAN key hierarchy. In UTRAN key hierarchy, an intermediate key KASMEU is newly brought by HSPA+, deducted by CK and IK. Further, KASMEU generates CKU and IKU, therein the CKU is used for ciphering user plane data and control plane instructions, the IKU is used for integrity protection for control plane instructions.
However, in current 3GPP standard, there is no generation and distribution method for KASMEU, CKU and IKU in the related art.